Process for producing regenerated cellulose filaments



April 2, 1963 SAlCHl MORIMOTO PROCESS FOR PRODUCING REGENERATEDCELLULOSE FILAMENTS Filed Feb. 25, 1961 INVENTOR Soichi MorimotoAttorneys 3,084,021 Patented Apr. 2, 1963 3 084,021 PROCESS FOR PRQDUCliNG REGENERATED CELLULOSE FILAMENTS Saichi Morimoto, 191Kurumaji-cho, Karnide, @tsn, Japan Filed Feb. 23, 1961, Ser. No. 102,082Claims priority, application Japan Feb. 29, 1960 13 Claims. (Cl. 18-54)This invention relates to novel regenerated cellulose fibres, productsformed therefrom, and to processes for producing the same.

The industry of viscose regenerated cellulose fibres has been makingsteady developments in spite of the fact that various other and novelsynthetic fibres have been developed and appeared on the market. Amongthe products of viscose regenerated cellulose fibres, those finding anddeveloping a market most successfully today are (l) regeneratedcellulose yarns for industrial uses such as rayon cords forreinforcement of tires, (2) crimped woollike regenerated cellulosefibres and (3) cotton-like re generated cellulose fibres with hightenacity and high wet modulus. In these fields, however, it is stillrequired, in common, to further improve the mechanical properties ofviscose regenerated cellulose fibres. lit is also desired that theirspecific properties depending upon the particular field of use hefurther improved. Among the persistently sought are, for instance, anincrease in the number of crimps, improvement in crimp stability,increase in fatigue resistance of the fibres.

Accordingly, it is the general and primary object of this invention toprovide improved viscose regenerated cellulose fibres with variousexcellent properties to meet the demands outlined above, and to provideprocesses for preparing the same.

More particularly, it is an object of this invention to provide a noveland improved process for producing viscose regenerated cellulose fibresof high tenacity and increased fatigue resistance suitable as fibres forreinforcement in industrial uses.

Another object of this invention is to provide a novel and improvedprocess for producing cotton like viscose regenerated cellulose fibresof high tenacity and lower water swelling or high wet modulus.

It is a further object of this invention to provide woollike viscoseregenerated fibres having more than 30 inherent crimps per inch, and toprovide a novel method for producing the same.

It is a still further object of this invention to provide viscoseregenerated cellulose fibres of the type mentioned above which arefurther improved in their crimp stability, and also to provide a novelresin treatment for producing the same.

Other objects of the invention will become apparent from the followingdetailed description.

The drawing is a schematic representation of an embodiment of theinvention.

Viscose regenerated cellulose fibres have heretofore come to be improvedin their properties due to repeated studies and efforts made in the art.For example, the so-called high tenacity rayon has come to be produced,with an outstanding commercial success, by the development of stretchspinning process with two spinning baths. Furthermore owing to thediscovery of certain additives sometimes referred to as coagulationmodifiers, the high tenacity rayon has further been improved soremarkably as to be called super high tenacity rayon. On the other hand,recently, through optical, X-ray and chemical researches, the innerstructure of viscose regenerated cellulose fibres has come to bedisclosed. Thus, it has now come to be recognized in the art that theproperties, particularly mechanical properties of the viscoseregenerated cellulose fibre depend upon the degree of orientation anddegree of crystallinity of the cellulose molecules forming the fibre,and that these orientation and crystallinity degrees of cellulosemolecules largely depend upon or are greatly influenced by theparticular mechanical stretch imparted to the viscose gel yarn duringits passage through coagulating and regenerating baths.

However, no industrially applicable work hasbeen reported up to thepresent to determine what magnitude of stretch should be imparted tosuch gel yarn in what stage in the continuous process of the yarnformation to bring about most desirable properties of the ultimate yarndue to the internal structural change resulted from such stretch. Thereason for this is in that there has been accomplished no satisfactoryor practical method for promptly determining an analyzing(quantitatively) the accurate number of residual xanthate groups ascontain in viscose gel yarn at any stage in the spinning process fromthe viscose to the final or ultimate yarn, or at any stage during thespinning process from the extrusion stage of the viscose through aspinneret up to the final yarn which has completed the regeneration.

Various proposals have heretofore been made to determine the number ofxanthate groups contained in a viscose gel yarn. All of these knownmethods have commonly been characterized by directly measuring theamount of combined alkali or xanthate groups in the gel yarn. Howeverthey have been unreliable particularly because of inevitable errorsincurred in the process of measurement such as in discontinuation of thedecomposition reaction of the cellulose xanthate, purification of theproduct to be measured, and removal of by-products, etc., and resultinginaccuracy of the value obtained.

It has now been found that it is possible to promptly determine theaccurate number of residual xanthate groups without the drawbacks of theknown methods, by taking a viscose gel yarn at any stage of spinningprocess, treating the yarn with an alkaline ammonium salt solution toconvert all of the sodium xanthate groups present into the ammoniumxanthate groups and simultaneously discontinue the decompositionreaction, washing the so treated yarn to remove any excess or freeammonium ions, decomposing the ammonium cellulose xanthate, and thenquantitatively analyzing the ammonium salt formed by the abovedecomposition. More particularly, for example, a partially orincompletely regenerated viscose gel yarn in an amount corresponding to0.25 to 0.35 g. of dry cellulose is taken up at any desired stage ofspinning process into a cooled (e.g. below 5 C.) ammonial alkalineammonium salt aqueous solution (saturation) to discontinue thedecomposition of the xanthate. The mixture is left to stand for about 5minutes to substitute all the residual or remaining xanthate groups withammonium ions. Then the whole is transferred into a cooled wateralcohol(4:6) mixture and washed for 15 minutes repeatedly while replacing thewashing liquid so as to remove free or excess ammonium ions. After thispurification the ammonium xanthate now formed is decomposed in a 0.5%hydrochloric acid to form ammonium chloride. According to this methodany insoluble ammonium salt is formed in the purification. Thedecomposed product is filtered to separate the regenerated cellulose,which is washed and dried, then weighed (this weight is represented by Sin gram). The filtrate is made alkaline with sodium hydroxide in around-bottomed flask, which is connected with a condenser to subject thesolution to distillation. Ammonia gas distilled out thereby isintroduced into a N sulfuric acid (A cc.). After confirming that thedistillation of ammonia has been completed, the sulfuric acid solutionis titrated with N sodium hydroxide.

, The amount consumed in this titration is represented by B cc. Throughthis measurement, the number of the (A-BgXLGZ Residual xanthate ratio(percent) This residual xanthate ratio is equal or corresponds, in thechemical nature, to the cellulose xanthate ratio (or gamma number) in aviscose. However, the important significance of the residual xanthateratio in this invention is in that it is in respect of a viscose gelyarn and not of a viscose solution before spinning. For convenience, theresidual xanthate ratio having the meaning substantially same as givenabove is referred to as RX hereinafter. The values RX as given in thisspecification and examples have been determined by the particularprocedure just mentioned above, but it would be understood by thoseskilled in the art that the procedure can be modified without departingfrom the principle, and therefore the residual xanthate ratio referredto in this invention generally means a ratio (percent) of the number ofxanthate groups in a viscose gel yarn with respect to the unit ofglucose constituting the cellulose in said yarn and its method ofmeasurement is not limited to the above indicated particular one,although this is believed to be most convenient and reliable at thepresent.

As described before I have succeeded in accurately and promptlydetermining the residual xanthate ratio (RX) of a viscose gel yarn onthe way of its regeneration, and therefore I have been able to observeand investigate in detail the process of coagulation and regeneration ofa viscose yarn during spinning. Particularly, the effect of stretch invarious degree imparted to the viscose gel yarn at various stages on theorientation and/or crystallization of cellulose molecules constitutingthe yarn has been carefully observed and investigated.

From this work, it has been found that the gel structure of a viscoseyarn being subjected to stretching has great influence upon theproperties of the ultimate yarn, and also that the conditions of aviscose gel yarn and its treatment should be critical to improve theproperties of the ultimate yarn.

As a result, it has been found that, generally, when a highly xanthatedviscose is extruded into an aqueous acidic precipitating bath to form ayarn, and the yarn is adjusted or controlled so as to be within RX 40-20just before being stretched, and then the yarn is stretched twice ormore in a plurality of successive aqueous regenerating baths (in whichany bath is not weaker in the regenerating power than that of thepreceding bath), there are obtained excellent orientation and/orcrystallinity of the cellulose molecules which remarkably improve theproperties of the resulting ultimate yarn.

It has also been found that, in the above case, when the adjustment ofRX 20-40 is effected under substantially relaxed or non-stretchedcondition in a secondary bath having not more than /2 acidity of theprimary or fibre-forming bath and hence having a low regeneration power,the effect of the subsequent stretching is more remarkable. The presentinvention is based upon this finding or principle.

The above principle is applicable to a spinning process wherein aviscose of an ordinary viscosity less than about 150 poises (usually100-50 poises) is spun into a Mueller-type spinning bath to produceyarns with a skin formed by the coagulating action of sulfates in thebath, as well as to a spinning process wherein a viscose of a highviscosity (more than about 150 poises) is spun into a bath having a poorregeneration and coagulation power to form yarns having substantially noskin.

Viscose which may be used in this invention may be prepared according tothe conventional methods by dissolving wood pulp or cotton linter pulp.However, the present invention requires a highly xanthated orsubstantially unripened (at least 50% in xanthate ratio or more than 50in gamma number) at extrusion, and therefore an alkali celluloseprepared from a cellulose substance should be xanthated with carbondisulfide in an amount more than 40% based upon the weight of thecellulose, and the viscose after the preparation should be kept at alower temperature (e.g. below 15 C.) so as to prevent the progress ofthe ripening as much as possible. The aging degree of the alkalicellulose may be suitably selected depending upon the desired degree ofpolymerization of the cellulose.

The substantially unripened or highly xanthated viscose thus prepared isspun in accordance with the principle of this invention mentionedbefore. This may conveniently be carried out with a four aqueous bathsystem, as shown in the drawing, consisting of a primary bath, 3, whichmay be referred to as fibre or yarn forming bath, a secondary bath, 6,which may be referred to as residual xanthate ratio controlling bath, athird bath, 10, which may be referred to as stretching bath and a fourthbath, 17, which may be referred to as regenerating and setting bath.

The primary bath or yarn forming bath, 3, is the bath for forming a gelyarn, 4, from a viscose extruded therein through a spinneret or spinningnozzle 12, connected to a source line, 1. In case the viscose is aboutpoises or less, an ordinary Mueller-type bath solution containingsulfuric acid, sodium sulfate and zinc sulfate and heated above normaltemperature is required to be used in the primary bath, while when theviscose is of a viscosity higher than about 150 poises a bath solutioncontaining a smaller amount of sulfuric acid and sodium sulfate and avery small amount of zinc sulfate and being kept at a temperature aroundor below normal temperature is required to be used.

The secondary bath, 6, or residual xanthate ratio controlling bath isthe bath for adjusting the residual xanthate ratio of the filament yarnformed in the primary bath so as to be within 20-40%. It is necessarythat the re generating power of the secondary bath be smaller than thatof the primary bath and it is preferable that the acidity of thesecondary bath is kept about or less than /2 that of the primary bath.

During the passage through the primary and secondary baths the gelfilament yarn should have applied thereto to it as little stretch aspossible or no stretch at all so as to substantially avoid anyelongation of the yarn at these stages.

The third bath, -10, or stretching bath is the bath for imposing a firstand positive stretch on the gel filament yarn during its passagetherethrough. The third bath may be of the same composition andtemperature as the secondary bath. Generally it is preferable, however,to use a bath with regenerating power a little stronger than that of thesecondary 'ba-th so as to decompose 4060%, at most 70%, of the residualxanthate groups (in the gel yarn just before entering this bath) duringthe stretching process in this bath.

The fourth bath, 17, or regenerating and setting bath is the bath forimposing a second stretch on the gel filament yarn and for substantiallydecomposing the remaining xanthate groups to set the internal structureof the regenerated cellulose yarn.

As mentioned before the primary bath or viscose filament yarn formingbath according to this invention may generally be classified into twotypes depending upon the viscosity of a viscose employed. A series ofthe baths following to the primary bath also vary in their compositionsand other conditions depending upon the primary bath. More particularly,the primary bath and hence the subsequently associated bath vary intheir conditions depending upon whether (A) the viscosity of thespinning viscose solution is less than about 150 poises or (B) it ishigher than about 150 poises. In conjunction with the baths, filamentguide rolls 5, 7, 8, 11, 12, 15 and 16 are employed. As prime movers,godet rollers 9, 13 and 14 are placed respectively after the second,third and fourth baths.

(A) SPINNING A VISCOSE OF LESS THAN ABOUT 150 POISES The degree ofpolymerization of cellulose in a viscose to be employed in the case of(A) may be ordinary one (eg about 250-400) or may be high (cg. more thanabout 500). However it is necessary to make its viscosity below about150 poises, preferably within about 50-100 poises, by controlling thecellulose content depending upon the polymerization degree. It isgenerally preferable to use a viscose containing 3-11% cellulose and3-13% total alkali and whose combined carbon disulfide amount is atleast 50%, preferably 75-90%, as expressed by xanthate ratio (or gammanumber).

A Mueller-type bath is used as the primary or filament forming bath, andthe subsequent spinning conditions are selected in accordance with the,principle of this invention mentioned hereinbefore. It has been foundthat the use of the following baths with conditions indicated givesatisfactory results.

Primary Bath General range Preferable range Sulfuric acid Sodium sulfaterz.[l- 180-300.

Zinc sulfate .g./l 40-80.

Temperature 55-65.

Travel length (Immersion) Not so as to re- Approximately for duce RX offilaneutralizing the ment below viscose alkalin- 20%. ity.

Stretch (as little as] possible) Secondary Bath General Preferable rangerange Sulfuric acid g./l-. 5-30 -25 Sodium sulfateg./l 30-120 80-100Zine sulfate g./l 0-100 10-30 Temperature 0.- 5-30 10-20 RX of yarn justbefore entering the thlrd bath percent- -40 -35 Str (as little alspossible) Third Bath General Preferable range range Sulfuric acid g./l10-50 25-35 Sodium sulfate ./1 -120 50-{30 71nc sulfate /1 0-100 10-30Temperature. 10-50 25-35 Stretch percent 30-100 50-80 Fourth BathGeneral Preferable range range Sulfuric acid 50-70 Sodium sulfate Lessthan 30 Temperature 80-100 Stretch 30-50 The yarn obtained in this caseof (A) is useful because of its remarkable high tenacity and highfatigue resistance as cords for reinforcement in industrial uses, suchas cords for reinforcement of automobile tires and hoses; and forreinforcement fabric or cords of conveyor belts, etc. The yarn is, ofcourse, useful as usual textile uses.

(A) SPINNING A VISCOSE OF LESS THAN ABOUT 150 POISES FOR PRODUCINGCR-lMPED FIBRES WITH MORE THAN 30 PERMANENT CRI-MPS PER INCH It has beenfound that when a particular range of conditions among those in the caseof the above mentioned (A) is selected, there is obtained a filamentyarn which can be, through a conventional after-treatment, effectivelycrimped so as to have a number of permanent crimps more than 30 perinch. For this purpose, it is preferable to use a viscose having ax-anthate ratio between -75%. The primary bath is selected as follows:

Sulfuric acid ....g./l -100 Sodium sulfate g./l 250-350 Zinc sulfate-g./l 40-70 Temperature C- 65-75 Stretch As little as possible Thesubsequent spinning conditions may be same as those of (A) indicatedbefore, but it is preferable that the residual xanthate ratio (RX) ofthe filament just before entering the third bath is controlled to be30'- 40%. Crimp development may be effected by, any suitableconventional manner. For example the crimp formation can be carried outby relaxing the regenerated filament yarn (cut into staple or not),under non-tensioned condition, into a cellulose swelling liquid such aswater, warm Water, a dilute aqueous solution of sodium hydroxide and thelike. The number of permanent crimps to be formed somewhat depends uponthe fineness of filaments spun. Generally, the coarser the filament is,the crimp number is less. However, in accordance with this invention,even when each filament is 10 deniers or above it is possible to formabout 30 or more crimps per inch. In case of fineness of 1-3 deniers,the number of crimps per inch would come up to 50-70. The crimpedfilaments or staple fibres obtained in the case of (A) are useful aswool-like fibres. Particularly, those having more than 50 inherentcrimps per inch obtainable according to this process are entirely noveland unprecedented in the art. These crimps are not lost by usualhandling or mechanical stretching. Even if the crimp is partly lost byrepeated carding, combing and other severe mechanical handling it iseasily recovered by simply suspending the fibre in Water or otheraqueous swelling liquid such as a dilute aqueous solution of sodiumhydroxide, in the absence of tension. Thus, the crirnped fibres of thisinvention, even with such increased number of crimps show about 70-100%when measured by the crimp recovery from stretch test (this may bereferred to as a wet meth- (*B) SPINNING A VISCOS'E OF MORE THAN ABOUT150 POISES I The high viscosity (higher than about 150 poises) ofviscoses may be obtained by increasing the content of the viscosecellulose or the cellulose polymerization degree in a conventionalmanner well known in the art. It is generally preferable to use aviscose containing 3-ll% cellulose and 3-13% total alkali and whosecombined carbon disulfide amount is at least 50%, preferably -90%, asexpressed by xanthate ratio (or gamma number).

In the present case (B) the primary or filament forming bath isconditioned so as to be poor in the coagulating and regenerating power,and the subsequent spinning conditions are selected in accordance withthe principle of this invention mentioned hereinbefore. It has beenfound that the use of the following baths with the conditions indicatedgive satisfactory results.

s,os4,021

Primary Bath General range Preferable range Sulfuric acid g./l Less than60 15-45.

Sodium sulfate g./l Less than 100 30-70 Zine sulfate.-. g./l Less than 5Less than 1.

Temperature. (3.. -30 -20.

Travel length (Immersion)- Note so as to reduce RX of filament belowApproximately for neutralizing the viscose alkalinity.

Stretch (as little als possible) Secondary Bath General range Preferablerange Less than 30 20S0 0-30 Sulfuric acid g./l Sodium sulfate--. g./1.-Temperature RX of yarn just before entering the third bath percentStretch 20-40 25- (as little as possible) Third Bath General rangePreferable range Sulfuric acid g./l Less than 30 Sodium sulfate- .g./l..20-80 Temperature. G 0-30 Stretch 30-150 Fourth Bath General rangePreferable range Sulfuric acid Sodium sulfate ponds (coagulationmodifiers) cooperate with the zinc sulfate and serve to reduce thedegree of primary gel swelling of the gel filaments, and therefore theuse of such modifiers is particularly useful in cases of the abovementioned (A) and (A') or where a Mueller-type bath is used as theprimary or filament forming bath for a viscose having a viscosity lessthan about 150 poises.

Among such compounds are, for example, polyoxyethylene mercapt-ans ofthe formula:

wherein R is a member selected from the group consisting of alkyl, aryland cycloalkyl, R is a member selected from the group consisting ofhydrogen and alkyl groups containing 1-4 carbon atoms, and n is aninteger at least equal to 1.

Examples of the compounds expressed by the above formula arediethyleneglycolbutylmercaptan, decaethylencglycolpropylmercaptan,pentadecaethyleneglycolphenylmercaptan,decaethyleneglycolbutylmercaptan, etc.

Aliphatic and alicyclic amines are also useful as the coagulationmodifiers, among which are, for example, triethanolamine, triethylamine,cyclohexylamine, benzylaminc, etc.

The salts of N-substituted dithiocarbamic acid are also useful, amongwhich are, for example, amyl dithiocarbamate, cyclohexyldithiocarbamatc, N-methylcyclohexyl dithiocarbamate, methyldithiocarbamate, etc.

Further examples of the compounds useful as the coagulation modifiersare those having the following general formula:

wherein each of R and R is a member selected from the group consistingof hydrogen, alkyl and aryl, n is an integer equal to at least 1. Amongthose compounds expressed by the above formula are, for instance,polyethyleneglycol, phenoxycthanol, ethoxyethoxyethanol,butoxylethoxyethanol, etc.

Among other compounds useful as the coagulation modifiers aremercaptoamines and N-substituted mercap todithiocarbamatcs, such asB-mercaptoethylamine, 'y-mcrcaptopropylamine, orthoaminothiophenol,N-substituted- B-mercaptoethylcarbamate, etc.

No further explanation would be required on these and other coagulationmodifiers because they are well known per se in the art.

The amount of these modifiers to be present in the viscose may varydepending upon the particular viscose, spinning speed and bathconditions. Generally, good results are obtained if the modifier(s) isused in an amount from 0.1 to 1.0 millimolc per grams of the viscose. Alarger amount of the modifiers over the range recited above may be used,but the effect of the modifier is not progressively enhanced by such anexcess amount of use.

The incorporation or addition of such modifier to a viscose may becarried out at any stage in the process of preparation of the viscose.For example, it is possible to predissolve or predisperse the modifierin a dilute aqueous solution of sodium hydroxide to be used later fordissolving a cellulose xanthate. Alternatively, it may be added directlyto the viscose.

As previously mentioned herein, a two-bath stretch spinning system isknown to produce the so-called high tenacity rayon or super hightenacity rayon. The conventional two-bath stretch spinning process ischaracterized by forming a gel filament yarn in the primary bath andthen immediately stretching the so formed gel yarn in the secondary bathto effect orientation of the cellulose molecules. This conventionalprocess has inherent defects, that is an improvement of one respect ofthe fibre properties, such as tenacity has inevitably accompaniedsacrifice in other valuable properties.

In sharp contrast thereto, according to the novel process of thisinvention, the gel yarn formed in the primary bath is not immediatelystretched but is controlled so as to obtain a particular regenerationstate with a stretch as little as possible, and thereafter it isprogressively regenerated while being subjected to suitable successivestretching during its passage through the subsequent successive baths inwhich the regenerating power increases progressively. By this novelspinning process I have produced filaments having increased tenacitycomparable with the known two-bath spinning process with additionaloutstanding properties now persistently sought in the regeneratedcellulose industry.

In carrying out the spinning process of this invention any suitableapparatus may be used so far as it is adapted to fulfill the spinningconditions as specified above. Most typically, the four baths arearranged in series at suitable intervals, each being provided withsuitable guides. A viscose is extruded through a spinneret into theprimary bath. The filaments formed in the bath are guided upwardly outof the bath to a guide roller located between and above the primary bathand sec ondary bath. Since the filaments must be controlled so as tohave a residual xanthate ratio from 25-35% when entering the third bath,the travel or immersion length of the filaments within the primary bathshould be selected so that the filaments leaving the primary bath do notbecome below about 20% in the residual Xanthate ratio.

jet velocity or rate at the spinneret, that substantially no tension isimposed on the filaments during their travel up to this godet roller.From this first godet roller the filaments are passed through the thirdbath while being guided by suitable guides therein and, after leavingthe bath, are taken upwardly by a second godet roller located betweenand above the third bath and the fourth bath. While passing through thethird bath the filaments are stretched due to a differential in speedbetween the first and second godet rollers. From this second godetroller the filaments are passed through the fourth bath while beingguided by suitable guides therein and, after leaving the bath, takenupwardly by a third godet roller located at a short distance beyond thefourth bath. While passing through the fourth bath the filaments arestretched due to a differential in speed between the second and thirdgodet rollers. From the third godet roller the filaments may be passedto a conventional purification apparatus such as for washing with waterfollowed or not followed by refining, bleaching, etc. It will beunderstood that if the secondary bath and the third bath are identicalin the composition and temperature, a single bath may be used thereforbut the second godet roller is arranged above the bath at a suitableposition. a

Generally, the spinning speed (final wind-up speed) is 20-80 m./min. forthe process of (A) and (A'), and is -30 m./min. for the process of (B).

The regenerated cellulose fibres produced by the novel multi-bathspinning process of this invention as described above and products suchas fabrics made of such fibres have outstanding properties and are veryuseful as such. However, sometimes, it may be desired that these fibresand their products have more excellent compressive resiliency, crimprecovery from stretch in dry state and other properties. It has beenfound that these desirable additional properties are obtained if theseregenerated fibres or their products are subjected to the particularresin treatment which will be fully described hereinlater. For example,when the crimped fibres obtained in the above mentioned process (A') areresin-treated as hereinbelow described their crimp recovery from stretch(in dry state) when tested in accordance with the procedure ashereinlater described attains to a value from about 80% up toapproaching 100%.

(C) RESIN TREATMENT It has been conventional in the art of resintreatment for such purpose to employ a preor primary polymer (orcondensate) of urea-formaldehyde resins, melamineformaldehyde resins,etc. The primary condensate is applied to fibres or their products andis then heat cured thereon. densates are, as against the monomers(methylol urea, methylol melamine), so large that it is difficult forthem to penetrate into very small spaces in the internal fi brestructure or crystalline structure. Therefore, a considerably largeamount of the resin is required to attain a satisfactory effect of suchtreatment, and furthermore the resin unevenly adheres only on thesurface area of the fibre, so that there have been various drawbacksthat the product is hard in hand feeling, a large amount of the resin isremoved upon laundering with a result of loss of the effect of the resinfinish.

However, the molecules of these primary con- 7 It has been proposed toimpregnate fibres with a sub stance such as urea and thiourea which isreactive with formaldehyde, and then to react it with formaldehyde toeffect resin formation in the fibres. However, said substance easilyforms its dimer so that a subsequent reaction with formaldehyde becomesdifficult. Thus, a satisfactory effect of resin finish is notobtainable. Further drawbacks of this method are that the finish has nogood resistance to laundering and that the so treated fibresconsiderably lose the strength.

If fibres could be impregnated with melamine in the form of monomer andnot as a primary condensate with formaldehyde and then formaldehydecould be allowed to react with the melamine in the fibres to effect theresin formation, an excellent resin finish should be obtained. However,since melamine is so hardly soluble in water that such melamine resintreatment has been practically impossible. Although it is possible :toincrease the solubility of melamine by converting it into salts ofstrong acids such as hydrochloric acid, the use of such strong acidsalts would cause discoloration and loss of strength of the treatedproduct during the heat treatment and the product would be impaired inappearance and feeling.

It has now been found that an excellentresin treatment can be effectedby impregnating fibres or articles made thereof with an aqueous solutionof a salt of melamine with an oxy acid containing hydroxyl group(s) inthe molecule, such as lactic acid, glycolic acid, thioglycolic acid,gluconic acid, etc., and then allowing formaldehyde gas (vapor) to atthereon in the presence of a small amount of water. As these melaminesalts of oxy acids are high in solubility in water they are advantageousin many respects. Furthermore as they are salts of weak acids there isno fear of discoloration and loss of strength of the fibres in the heattreatment, and advantageously they serve as a good catalyst in thecondensation reaction during the heat cure treatment. Further advantagesof this novel method are that since melamine monomers in the form of asolution sufficiently penetrate into very narrow spaces of the internalfibrous and crystalline structure the use of a relatively small amountof the material affords excellent results or increase in elasticrecoverability, crease resistance, shrink resistance and dimensionalstability, and that as the resin is deeply distributed in the internalfibrous structure the effect of the resin finish is rather permanentaland is excellent in resistance to laundry.

In carrying out the novel process of resin treatment according to thisinvention, it is suitable that an oxy acid is'reacted with melamine inthe proportions of 0.3-3.0 moles of the oxy acid per mole of melamine.In an aqueous solution containing 0.5 to 4% of the melamine 'salt, at atemperature from normal temperature to. the

boiling point of the solution, fibres or their products such astextiles, knitted fabrics, etc. to be treated are immersed andimpregnated with the solution. The impregnated article is squeezed orcentrifuged to remove an excess liquid and dried at a temperatureranging from 60 to C. Thereafter formaldehyde vapor is allowed to act onthe fibres or article. The temperature of the formalde hyde vapor may befrom normal temperature to 100 C., but preferably 30 C. to 50 C. If thetemperature at the formaldehyde treatment exceeds 100' C. there is adanger that the formaldehyde is connected in a polymerized form tomelamine with a result .to cause enbrittlement of the fibres. Inreacting formaldehyde with melamine as adsorbed in the fibres, thepresence of 10 to 30% (based on the weight of the fibres) of Water isrequired. However, the-presence of an excessive amount of water shouldbe avoided because it would induce a violent reaction which wouldembrittle the fibres or impair the feeling of the fibres. If the amountof water is insufiicient the reaction is difficult to proceed. Theamount of water as considered here means that contained in theformaldehyde vapor plus that remaining in the fibres or their products.The time for the reaction varies widely from about 10 minutes to 5 hoursdepending upon the temperature. As for formaldehyde, a moistformaldehyde vapor produced by heating at a temperature below 80 C. a30-40% aqueous formalin may be employed. Alternatively, formaldehyde gasproduced by heating at a temperature below 100 C. para-formaldehyde maybe used. It is preferable that the amount of formaldehyde to be employedis about 2 to 5 moles per mole of melamine as contained in the fibres.After the treatment with formaldehyde vapor, the article is dried at60-100 C. for 5-15 minutes, and then set or cure the resin by a heattreatment at a temperature of 120-1 60 C. for a period of time requiredfor setting the resin, for example more than 2 minutes. The article isthen washed to finish, or subjected to a conventional after-treatment.

For illustrative purposes, the following specific examples are given.Among them, Examples 1-4 are to illustrate the multi-bath spinningprocess of (A), Examples 5-7 relate to the process of (A') and Examples8-10 are to illustrate the spinning process of (B). Examples 11-14 areto illustrate the resin treatment of (C).

EXAMPLE 1 A cotton linters cellulose pulp was steeped for 2 hours in anaqueous solution containing 230 g./l. of sodium hydroxide and the alkalicellulose was pressed until to be 2.6 times the weight of the originalpulp used. After shredding the alkali cellulose in a conventionalmanner, carbon disulfide in the amount of 50% based upon the weight ofa-cellulose was added thereto, and the xanthation reaction was thenallowed to proceed for 3.5 hours while elevating the temperature from 20to 28 C. After the reaction the cellulose xanthate was dissolved byadding thereto predetermined amounts of sodium hydroxide and water togive a viscose containing 7.0% cellulose and 6.0% total sodiumhydroxide. After ripening at 5 C. for hours, its viscosity was 91 poisesand the xanthate ratio was 70%.

The viscose in the substantially unripened state was spun through aspinneret having 720 holes of 0.06 mm. diameter into a primary bathunder the following condition to form viscose gel yarn:

Sulfuric acid 120 g./l.

Sodium sulfate 300 g./l.

Zinc sulfate 5O g./l.

Temperature 60 C.

Travel length (immersion) As required for approximately neutralizingviscose alkalinity. Then this gel yarn was passed through the followingsecondary bath;

Sulfuric acid g./l 15 Sodium sulfate g./l 60 Zinc sulfate g./l 50Temperature C 15 composition:

Sulfuric acid g./l Sodium sulfate g./l 70 Temperature C 20 The yarn,while passing through this bath, was stretched 60% by a differential inspeed between a second godet roller loca-ted beyond the third bath andthe first godet roller. The yarn thus subjected to a low temperaturestretch was Wound up on the second godet roller.

Then the yarn was passed from this second godet roller into and throughthe following fourth bath;

Sulfuric acid g./l 100 Sodium sulfate g./l 150 Temperature C 70 Theyarn, while passing through this bath, was stretched 30% by a differencein speed between a third godet roller (peripheral speed about 30m./min.) located behind the fourth bath and the second godet roller, andwas completely regenerated during receiving this high temperaturestretch to give a yarn of 720 filaments of 1100 deniers. The yarn wassuccessively washed with water, oiled and dried and was wound up on abobbin. To a single strand of this yarn was imparted a twist in theamount of 12.5 per inch and two such twisted single yarns were twistedtogether into a cord while applying 12.5 twists per inch. The propertiesof this cord are given below:

The values given in the above parentheses are of cord, for comparison,obtained by the following two-bath stretch spinning method. That is tosay, the viscose prepared by the same method as of this example was,after ripening at 15 C. for 20 hours, spun at a viscosity of 83 poisesand a xanthate ratio of 63% into the following primary bath under thefollowing condition:

Sulfuric acid g./l 130 Sodium sulfate -g./l 250 Zinc sulfate g./l 60Temperature C 60 The yarn which, after leaving the primary bath, was 23in the residual xanthate ratio was then passed through the followingsecondary bath under the following condition:

Sulfuric acid g./l.. Temperature C 98 During the passage of thissecondary bath the yarn was subjected to stretch between godets andcompleted the regeneration, to give a yarn of 720 filaments of 1100deniers. The yarn was then washed with water, oiled and dried, and wastwisted under the same conditions as in the above example into a cordfor testing.

EXAMPLE 2 A dissolving wood pulp was steeped for 2 hours in an aqueoussolution containing 230 g./l. of sodium hydroxide and the alkalicellulose was pressed until to be 2.7 times the weight of the originalpulp. Then the alkali cellulose was shredded at 30 C. for 15 hours.Immediately there after or without being aged, to the alkali cellulosewas added 45% carbon disulfide (based on the weight of a-cellulose), andthe xanthation reaction was then allowed to proceed for 3 hours whileelevating the temperature from 20 C. to 28 C. After the reaction thecellulose xanthate was dissolved in a sodium hydroxide solution in whichdecaethylene glycol tertiary butyl mercaptan had been dissolved in suchan amount as to be 0.3 millimole/ grams of viscose. Thereby a viscosehaving a cellulose content of 6% and a total sodium hydroxide content of6% was obtained. This viscose was deaerated while being ripened at 5 C.for 20 hours, and was, under the conditions of a viscosity of 78 poisesand a xanthate ratio of 65%, extruded through a spinneret of 720 holes13 of 0.06 mm. diameter into a primary bath of the following conditions:

Sulfuric acid g./1 120 Sodium sulfate g./-l 300 Zinc sulfate g./l 50Temperature C 58 Travel length (immersion) As required for approximatelyneutralizing viscose alkalinity.

The formed viscose gel yarn was then immediately and, Without imposing atension as possible, passed into and through the following secondarybath:

Sulfuric acid g./l Sodium sulfate g./l 50 Zinc sulfate g./l 60Temperature C During the passage of this bath the yarn was stretched aslittle as possible, and the residual xanthate ratio of the yarn afterleaving the second bath was controlled so as to be The gel yarn was thenpassed into and through the following third bath:

Sulfuric acid g./l 30' Sodium sulfat g /1 50 Temperature C 15 The yarn,while being passed through the third bath, was stretched 60% by godetrollers located respectively before and behind the third bath. Theresidual xanthate ratio of the yarn leaving the third bath wascontrolled so as to be 15%. Then the yarn was stretched by in the fourthbath of the following condition:

Sulfuric acid g./l 60 Temperature C 80 Oven-dry breaking strength 4.68g./d.

4.02 g./d.). Oven-dry breaking elongation 10.4% (17.3%). Loss ofstrength after 2 hrs. at

Fatigue test with Goodrich cord tension vibrator (under load of 7 282minutes lbs.) (262 minutes).

The values given in the above parentheses are of cord, for comparison,obtained by the following two-bath stretch spinning method. That is tosay, the viscose prepared by the same method as of this example was,after ripening at 10 C. for 8 hours, spun at a viscosity of 65 poisesand a xanthate ratio of 60% into the primary bath of the followingcondition:

Sulfuric acid g./l 120 Sodium sulfate g./l 270 Zincsulfatefla g./l 60Temperature C The yarn (R.X. 20) was then completely regenerated whilebeing stretched 80% between godet rollers and being passed through thefollowing secondary bath:

Sulfuric acid g./l Temperature C 95 By this way, a yarn of 720 filamentsof 1650 deniers was obtained. The yarn was then washed with water, oiledand dried, and was twisted under the same conditions as in Example 1into a cord for testing.

EXAMPLE 3 An alkali cellulose prepared by the same operation as inExample 1 from a cotton cellulose pulp was shredded at 15 C. for 2hours. After the addition of 50% (based upon the weight of a-cellulose)carbon disulfide, xanthation reaction was allowed to proceed for 3 hourswhile elevating the temperature from 20 C. to 25 C. The highly xanthatedcellulose thus obtained was dissolved in a dilute aqueous solution ofsodium hydroxide in which cyclohexyl amine had been dissolved in such anamount as to be 2 millimoles/ grams of viscose. In this way, a highpolymerization degree, low cellulose content v-iscose having a cellulosecontent of 3.5%, a total sodium hydroxide content of 60% and an averagecellulose polymerization degree of 630 was obtained. This viscose was ofa xanthate ratio of 70% and a viscosity of 62 poises. This viscose,without being ripened, was extruded as in Example 1 through a spinneretinto the following primary bath:

Sulfuric acid g./l Sodium sulfate g./l 330 Zinc sulfate g./l 80Temperature C 60 The formed gel filament yarn was then immediately andwithout being stretched, passed into the following secondary bath:

Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 10 Sulfuricacid- -g./l- 20 Sodium sulfate g./l 70 Temperature C 30 The yarn whilepassing this bath was stretched by 70% at the low temperature betweentwo 'godet rollers. The residual xanthate ratio of the yarn afterleaving the third bath was controlled to be 14%. Then the yarn waspassed through the following fourth bath:

Sulfuric acid g./l 100 Sodium sulfate -1 g./l Temperature C 70 While theyarn was stretched by 40% at the high temperature in this fourth bath,it was completely regenerated to obtain a yarn of 1000 filaments of 1100deniers.

The yarn was successively washed with water, oiled and dried, and wasthen wound up on a bobbin (about 50 m./min.). The yarn was twisted intoa two-ply twisted cord under the same conditions as in Example 1. Theproperties of this cord are as follows:

Oven-dry breaking strength 5.02 g./d.

(4.10 g./d.). Oven-dry breaking elongation 10.6% (16.8%). Lossofstrength after 2 hrs. at

Fatigue test with Goodrich cord tension vibrator (under load of 7 225minutes lbs. (206 minutes).

Sulfuric acid g./l 100 Sodium sulf /-l 300 Zinc sulfate g./l 50Temperature C 60 The yarn (RX. 26) was thereafter completely regeneratedwhile being stretched 75% between godet rollers and being passed throughthe following secondary bath:

Sulfuric acid g./l 40 Temperature C 95 Thus, a yarn of 1000 filaments of1100 deniers was obtained. The yarn was then washed with water, oiledand dried, and was wound up on a bobbin. Thereafter, the yarn wastwisted into a cord under the same conditions as in Example 1.

EXAMPLE 4.

Sulfuric acid g./l 110 Sodium sulfate g./l 270 Zinc sulfate g./l 60Temperature C 63 The condition of the secondary bath (residual xanthateratio controlling bath) was as follows:

Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 15 Theresidual xanthate ratio of the gel yarn leaving the secondary bath wascontrolled so as to be 33%. The gel yarn which had not been stretched upto the passage through this secondary bath was then stretched by 60% inthe following third bath (low temperature stretching bath):

Sulfuric acid g./1 30 Sodium sulfate g./l 100 Temperature C 15 The yarnwas further stretched by 50% during the passage through the followingfourth bath (regenerating and setting bath):

Sulfuric acid ..g./l 100 Sodium sulfate g./l 150 Temperature C 95 Inthis bath the yarn was completely regenerated and was then wound up on abobbin (about 30 m./min.). Then, the yarn was cut into a staple lengthof 38 mm. and was refined and dried in a conventional manner. Theproperties of the staple fibres thus obtained are as follows:

Filament fineness deniers 1.5 Dry tenacity g./d 4.51 Wet tenacity g./d3.97 Dry elongation percent 18.8 Wet elongation do 23.3 Knot strength-g./d 3.55

The following Examples 5 to 7 are to illustrate the manufacture ofcrimped fibres according to this invention hereinbefore outlined under(A'). In these Examples the evaluation of the crimp recoverability wasmade by the crimp recovery from stretch test outlined in the beforementioned United States Patent No. 2,287,099.

EXAMPLE 5 A viscose prepared by the same operation as in Example 2except that beta-mercapto-ethyl amine was. added to the viscose in theamount of 3 millimoles/lOO grams of viscose, was filtered and deaerated.The viscose hav- The primary bath was as follows:

Sulfuric acid g./l- Sodium sulfate g./l 300 Zinc sulfate g./l 60Temperature C 63 The secondary bath was as follows:

Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 15 Up to thepassage through the secondary bath, the gel yarn was handled so as to bestretched as little as possible. The residual xanthate ratio of the yarnleaving the secondary bath was controlled to be 35%.

The third bath was as follows:

Sulfuric acid g./l 30 Sodium sulfate g./l 80 Temperature C 20 In thisbath, the gel yarn was stretched by 50% between godets.

The fourth bath was as follows:

Sulfuric acid g./I 60 Temperature C 97 In this bath, the yarn wascompletely regenerated while being stretched by 30%. The yarn was thenwound up on a bobbin (about 40 m./min.). The yarn was then cut intostaple length of 38 mm. and was immersed in hot water, in a relaxedstate, Crimps were developed thereby. During the subsequent purificationand bleaching, no substantial change in the crimp was observed. Afterthe fibre was refined and dried, the number of crimps was 60 per inch,and the properties of the fibre were as follows:

Filament fineness deniers 3.2 Dry tenacity -g./d 3.52

Wet tenacity ..g./d- 2.56 Dry elongation .Percent 23.2 Wet elongation do30.1 Crimp recovery from stretch do 95 EXAMPLE 6 A cellulose xanthateprepared by the same operation as in Example 1 was dissolved in apredetermined amount of a dilute aqueous solution of sodium hydroxide inwhich benzyl amine had been dissolved so as to be of a concentration of0.7 millimole/ 100 grams of viscose, to obtain a viscose containing 7%cellulose and 8% total sodium hydroxide. This viscose was immediatelyfiltered and deaerated and was then spun by the same spinning apparatusas in Example 1, at a xanthate ratio of 70% and a viscosity of poises.

The primary bath was as follows:

Sulfuric acid g./l Sodium sulfate g./l 350 Zinc sulfate g./l 40Temperature C 70 The secondary bath was as follows:

Sulfuric acid g./l 20 Sodium sulfate g./l 50 Zinc sulfate g./l 60Temperature C 20 Up to the passage through the second bath, the gel yarnwas handled so as to be stretched as little as possible. The residualxanthate ratio of the yarn leaving the secondary bath was controlled tobe 25%.

17 The third bath was as follows:

Sulfuric acid g /l 50 Sodium sulfate g /1 100 Temperature C 20 The yarnwas stretched by 60% in this third bath. The fourth bath was as follows:

Sulfuric id g/l- 30 Temperature C 90 In this bath, the yarn wasstretched by 30% and was completely regenerated. This yarn was Woundupon a bobbin (about 40 m./min.), and then cut into staple length of 38mm. The fibre was immersed under relaxation in water, whereupon 55permanent crimps per inch were developed on the yarn. After refining anddrying, the properties of the fibre were as follows:

Filament fineness deniers 2.5 Dry tenacity g./d 3.85 Wet tenacity 'g./d2.72 Dry elongation percent 20.2 Wet elongation do 29.2 Crimp recoveryfrom stretch do 100 For comparison, the same viscose which containedbenzyl amine in a concentration of 0.7 millimole/ 100 grams of viscoseand which contained 7% cellulose and 8% total sodium hydroxide wasprepared from the cellulose xanthate obtained by the same operation asin Example 1. After the viscose was filtered and deaerated, it was spunat a xanthate ratio of 70% and a viscosity of 85 poises into thefollowing primary bath:

Sulfuric acid ..g./l 80 Zinc sulfate g./l 320 Temperature C 70 Theviscose yarn formed in this bath was completely regenerated while beingstretched by 80% in the following secondary bath:

Sulfuric acid g./l Temperature C The yarn thus obtained was cut intostaple length of 38 mm. and was immersed in 1% aqueous solution so- 7dium hydroxide so as to develop crimps. After refining and drying, theproperties of the fibre were as follows:

Filament fineness der1iers 2.5

Dry tenacity g./d 2.86

Wet tenacity g./d 1.71

Dry elongation percent 22.6

Wet elongation do 25.6

Crimp recovery from stretch do 45 EXAMPLE 7 A cellulose xanthateprepared by the same operation as in Example 2 was dissolved in a diluteaqueous solution of sodium hydroxide containing no additive or modifierto produce a viscose containing 6% cellulose and 7% total sodiumhydroxide. This viscose, under the conditions of a xanthate ratio of 70%and a viscosity of 64 poises, was spun by the same spinning apparatus asin Example 1.

The primary bath was as follows:

Sulfuric acid"; ./1 70 Sodium sulfate -4 g./l 280 Zinc sulfate g./l 80Temperature C 65 The secondary bath was as follows: Sulfuric acid g./l10 Sodium sulfate g./l.. 100 Temperature C The residual xanthate ratioof the yarn leaving the secondary bath was controlled to be 28%.

18 The third bath was as follows: Sulfuric acid g./l 10 Sodium sulfateg./l 100 Temperature C 25 In this third bath, the gel yarn was stretchedby 60%. The fourth bath was as follows:

Sulfuric d g./l 100 Sodium sulfate -g./l 80 10 Temperature C 80 In thisfour-th bath, the yarn was stretched by 40% and completely regeneratedtherein. Then the yarn was Wound up on a bobbin (about 50 m./min.).After washing with water the yarn Was cut into staple length of 51 mm.and was immersed in an aqueous solution of 1% sodium hydroxide underrelaxed state, whereupon 40 crimps per inch were developed. Theproperties of the staple fibre obtained in this example were as follows:

Filament fineness deniers 2.0 Dry tenacity g./d 3.4-8 Wet tenacity g./d2.38 Dry elongation percent 18.3 Wet elongation do 25.0 Crimp recoveryfrom stretch do 75 EXAMPLE 8 An alkali cellulose prepared by aconventional method from a dissolving wood pulp was shredded and aged.

Then 70% (based upon the weight of u-cellulose) carbon disulfide wasadded thereto and the xanthation reaction was proceeded for 3 hourswhile elevating the temperature from 17 C. to 23 C. The cellulosexanthate was dissolved in -a cooled (10 C.) dilute aqueous solution ofsodium hydroxide, thereby a viscose having an average cellulosepolymerization degree of 350, a cellulose content of 10% and a totalsodium hydroxide content of 7% was obtained. This viscose, at aviscosity of 220 poises and a xanthate ratio of 78%, was spun with the aspinneret of 2000 holes and 0.05 mm. diameter. The first bath .was asfollows:

Sulfuric acid g./l Sodium sulfate -g./l 65 Zinc sulfate g./l 0.3Temperature C p 8 The viscose gel yarn formed in this bath was thenpassed into and through the following secondary bath:

Sulfuric acid g./l Sodium sulfate g./1

Temperature C The' gel yarn passed through the bath so as to bestretchedas little as possible and the residual xanthate ratio of the yarnleaving this bath was controlled to be 28%. This yarn after leaving thisbath was Wound up on a rubber godet of a peripheral speed of 5 m./min.

and therefrom passed into the third bath of the same temperature andcomposition as of the secondary bath where.

in it was stretched by 20% during the passage through the followingfourth bath:

same spinning apparatus as in Example 1 but through 1,9 EXAMPLE 9 Analkali cellulose prepared by a conventional method froma"cottoii1if1'trs cellulose pulp was shredded, and; 70% carbon disulfide(b'asedupon'tlie weight of a-CClllT- lose) was added ther etowithoutageing the alkali cellulose. After'the-xanthationas in Example 8,the cellulose xanthate was dissolved in a dilute aqueous solution ofsodium hydroxide. Thus a viscose havingan average cellulosepolymerization degree of 7 50, a cellulose con l I a I H *plesyanous.numencatvalues or test results llldlQatfld.

tent of 35% and a total sodium hydroxide content of was obtained.

This viscose, at aviscosity of 280 poisesand a xanthate ratioof 75 %l,wasspun with the same spinning apparatus asin Example 1. 5

' The first bath was as follows: Sulfuric acid; g./1 29 o ium. ul at 0Zing: sulfate g,/1 0.120 Temperature C The gel .viscose yarn afterleaving this bath was immediately passed .through. the followingsecondaryibathz Sulfuric acid 1 1.0 51

Sodium sulfate g 1 50 Temperature f C-- 15 The yarn was passed throughthe secondary bath so as to The stretched as little as possible, and theresidual xanthate ratio of the yarn leaving this-bath was controlled 4to be 27%. The yarn was passed from this bath through a godet roller(5,m./min.)' into the subsequent third bath havi'rigthe same temperatureand composition as of the second bath. During the passage through thisbath the yarn was stretchedby 110%, and the residual 'Xanthate ratio(R.X.) of the yarn leaving the bath was controlled; tobe Then 'theyarii'wascomplet ely regenerated whilebeihg stretchedby %fin the ren ntonnage Sulfuric Acid ..g./1..- 60 Sodium sulfate g./1 100 7, e p r turThe completely regenerated yarn was wound up ona bobbin-and wasthenrefined and'dried by a conventional manner. The properties of the yarnwere "as follows:

Filament fineness eniers 1.2 Dry tenacity; Zg;/d 5.63. We: tenacity g/d4.71 Dry elrifigatihn per c e nt 7.8 Wet elongationgnu; do.." 7.8

Emerald" An alkfi celluloseprepared by a conventional manner from acotton lin'ters cellulose pulp was shredded and. aged. Thereafter,%,,(based uponjthe'weight of a cellulpseYcarbo'ri disulfi'de was addedthereto, and the l xanth ation' reaction and"dissolution of theresulting, xanthate were effected by the same method in Example 8 .toprepa'r" a 'visc'ose "having" a cellulosecontent;

The average cllirlo'sepolynierization degree of the viscose was 480 Thisviscose at a"visc'o sit y of. 300 poises. and "a xapthate ratio of 73%was spun withwth e same spinning apparatusas in Example 8. The. primarybathw was'a's follows: K

Filament fineness deniers 1.5. Dry tenacity a g./d 4.82 we: tenacity;g'./d 4.10

Dr'yelong'atiomtm; percent 8.0 Wet elongation do 8.5

20 and was then treated the same as in Example 8. The properties of theyarn were as follows:

The following Examples 11-14 illustrate the novel resin treatmentaccording to.thisjnvention. In these Examwere determined the followingprocedures.

Tear strength: Measured by Pendulum methodtunit, g.).

Crease resistance: .Measured by Monsanto method (unit,

degree), directionplus filling direction.

Abrasion resistance: .Measured with Universal Weartester (unit, numberof times).

Compressiveresilienc'e: Cut fibres are piled up on a flat plate" andare" compressed by a column body "at a speed of 10 cm./min. When thepressure has reached 25.5 g./c'm.'-, the compression is discontinued andthe column body is returned'to the original position ata speed of 10cmL/min'. The same compression as in the above is againapplied.'Whilelthese procedures the pressure. variation is continuouslymeasuredby Instron (tensile tester) to findtthework done. If the. workdoneinfthefirst compression stroke is F and the :work done in the secondcompression stroke is F then the compressive resilience is representedasfollows:

Compressive resilience=, X

Stress relaxation coeflicient: The fibres are compressed as 1 applied tothe lower end, to measure the length of the filament (a m Then a load of50 mg. per denier is "appliedand the lengthtb cm.) of the filament is'measured after l minutef Then the load is removed and .upon -the lapseof '1 minute a load of 5 mgQis again applied to measure the length (ccm.). Then, the crimp recovering is represented as'follows:

Crimp recovery from stretch (dry state) =g X100 1 mole to lactic acid0.68 1110a Afterrem ovin g an the form ofa lacticacid saltin' amolejratio pfjmelamine excess solution, the fabric was dried to be 20%Zwater content. Then the fabric'was exposed to formaldehyde gas;geperated. by. heating. paraeformaldehydeto 50 C.,

After ,dryingat 85.....C. for .3 minutes, the fabric washeat-treated,at,.150i. C. for. 5 minutes, and was then washed with hotwater and dried. For comparison, ac-

cording to a conventional method, the same muslin fabric as in the abovewas soaked in a 6% trimethylol melamine solution containing 0.6%ofmagnesium chloride as a catalyst. Thereafter the fabric was dried at 85Cfor 5 minutes, and then heatftreated .at C. for 5 minutes. Then thefabr icwas washed with-hot water and Abrasion resistance (number oftimes) Crease resistance (degrees) Tear Deposition strength- (a) ofresin (percent) Lactic acid melamine- Trimethylol melamine.-. UntreatedEXAMPLE 12 Crimp recovery (percent) Stress relaxation cocifieientCompressive resilience (percent) Untreated Treated with glycolic acidmelamine r The crimped staple fibres so treated did not lose the crimpseven through carding operation.

EXAMPLE 13. I

A bulk of crimped staple fibres obtained in Example 6 was immersed in a3% solution of melamine lactate (melamine to lactic 'acid' inequimolecular proportions) at 70 C. After removing an excess solution bya centrifugal separation, the fibres were dried at 80 C. Then the fibreswere exposed to a 38% formalin vapor at 30 C. for hours, and then weresubjected to heat treatment at 160 C. for 3 minutes. The fibres thustreated were 78% in compressive resilience and 98% in crimp recoveryfrom stretch (in dry state). The fibres were spun and woven into muslin9. The properties of this fabric are as follows:

Deposit of Tear Crease resin strength resistance (percent) (g) (degree)Treated 4. 56 1,058 275 Untreated 1, 211 211 EXAMPLE '14 A weft sateenwoven from the staple fibres obtained in Example 8 was immersed in a 3%solution of melamine salt (containing 1.5% thioglycolic acid) at 60 C.After removing an excess liquid, the fabric was dried at 80 C. for 10minutes, and then exposed to a 37% formalin vapor at 50 C. for one hour.Thereafter the fabric was subjected to a heat treatment at 150 C. for 5minutes. The

(1) extruding highly xanthated viscose, containing 3-11% by weightcellulose and 3-13% by weight total alkali, said viscose having axanthate ratio of at least about 50 and a viscosity of less than about150 poises, into a primary aqueous acidic precipitation bath to form gelfilaments under substantially non-stretched condition,.said primary bathcontain-' ing 40-180 gms./l. of sulfuric acid,. 150-400 gmSL/l. ofsodium sulfate and 10-150 gms./l. of zinc sulfate and being maintainedat a temperature of about 45 to C., said gel filaments being controlledto be within 20-40 in residual xanthate ratio,

(2) passing the resultant filaments, under substantially non-stretchedcondition, through a secondary bath containing 5-30 gins/1. of sulfuricacid, 30-120 gins/l. of sodium sulfate and 0-100 gms./l. of zinc sulfateand being maintained at a temperature of about 5 to 30 C., said gelfilaments being controlled to be within 20-40 in residual xanthate ratioimmediately prior to stretching, and I (3) stretching said filamentsmore than twice while passing them through a third and fourth bath, saidthird bath being at least equal in regenerating power to the secondarybath, and containing 10-50 gms./l. of sulfuric acid, 30-120 gms/i. ofsodium sulfate and 0-100 gms/l. of zinc sulfate and being maintained ata temperature of about 10 to 50 C., said third bath reducing theresidual xanthate ratio by at most 70%, said fourth bath containing30-100 gms./l. of sulfuric acid and 0-200 gms./l. of sodium sulfate andbeing maintained at a temperature of above 50 C., the stretch at saidthird bath being 30 to and at said fourth bath, 10 to 80%, and

each successive bath in the plurality of baths being at least as strongin regenerating power as its preceding bath.

2. A process as claimed in claim 1 wherein the viscose is about 50-100poises in viscosity, the primary bath contains 60-150 g./l. of sulfuricacid, 180-300 g./l. of

sodium sulfate, 40-80 g./l. of zinc sulfate and is maintained at atemperature between 55 C. and 65 C., the secondary bath contains 10-25g./l. of sulfuric acid, 80- 100 g./l. of sodium sulfate and 10-30 g./l.of zinc sulfate and maintained at a temperature between 10 C. and 20 C.,the third bath contains 25-30 g./l. of sulfuric acid, 50-80 g./l. ofsodium sulfate and 10-30 g./l. of zinc sulfate and maintained at atemperature between 25 C. and 35 C., the fourth bath contains 50-70g./l. of sulfuric acid, less than 30 g./l. of sodium sulfate andmaintained at a temperature between 80 C. and 100 C., the stretch at thethird bath being 50-80% and the stretch at the fourth bath being 30-50%,and the residual xanthate ratio just before entering the third bathbeing 25-35%.

3. A process as claimed in claim 1 and particularly useful for theproduction of regenerated cellulose filaments having the property ofspontaneously crimping upon being immersed under relaxation in anaqueous liquid, wherein the viscose is 65-75% in the viscose xanthateratio (gamma number) and the primary bath contains 70-100 g./l. ofsulfuric acid, 250-350 'g./l. of sodium sulfate and 40-70 g./l. of zincsulfate and is maintained at a temperature between 65 C. and 75 C., therate of regeneration at the secondary bath being controlled so that thefilaments just before entering the third bath preferably have a residualxanthate ratio of 30-40% 4. A process as claimed in claim 1 wherein theviscose is more than about poises in viscosity, the primary bathcontains less than 60 g./l. of sulfuric acid, less than 100 g./l. ofsodium sulfate and less than 5 g./l. of zinc sulfate and is maintainedat a temperature between 0 C. and 30 C., the secondary bath containsless than 30 g./l. of sulfuric acid, 20-80 g./l. of sodium sulfate andis maintained at a temperature between 0 C. and 30 C., the third bathcontains less than 30 g./l. of sulfuric acid, 20-80 g./l. of sodiumsulfate and is maintained at a temperature between 0 C. and 30 C., andthe fourth bath contains 30-100- g./l. of sulfuric acid and 50-150 g./l.of sodium sulfate and is maintained at 23 a temperature above 20. C.,the stretch at the third bath being 3 0 l5 0% and the stretch at thefourth bathbeing -50%..

5. A,proce ss asclaimed in claim 1 wherein the-primary bathcontains.1545g./l. of sulfuric acid, -70 g. -/l. of sodiumfsulfa'teand. less than 1g./1. of zinc sulfate and.is-maintained atatemperature between 5 C. and20 C., the secondary bathcontains 5-15-g.'/l. of sulfuric acid, 40. .60g./l. o f so dium sulfate and is maintained a-tlatemperature between. 5C. and 20 C., the third bath contains-5 15 g./l. of sulfuric acid, g./l.of.sodiun1 sulfate and is maintained at'a temperature between 5 C. and20 C., and the fourth bath contains 40 70..g. l. of sulfuric acid'andg./l. of sodium sulfate andfismaintained at, a temperature between :30C. and 70 C., the stretch at the third bath being 60- and the-stretch atthe fourth bath being 10-30%, and theresidual xanthate ratio just'beforeentering the thirdbathbeing,25 35%.

6. A processaccordingtoclaim l wherein the.viscose. containsdissolvedtherein about 0.1 to 10 millimoles per 100.;grar'ns of theviscose of a coagulation modifier which lowers the-degree of primary gelswelling of the viscose filaments.

7. A process for treatingfilament produced according to a process-asclaimedin claim. 1, which comprises applyingjo the filament a solutionof a salt of melamine and an oxy.acid,j exposing the filament to aformaldehydevapor in thepresence of .a small amount of-water,andthensubjectingthe ,filamentto a heat treatment.

8. A. process as..claimed. .in claim 7 whereinthe salt consists ofmelamine and'an-oxy acid inthe proportions of 0.3-3.0 moles of the oxy.acid per mole of melamine. 35

9. Aprocessasclaimed in claim 7 wherein the solution contains 0.5 to 4%of the salt.

10. A process as claimed in claim 7 wherein the reaction of formaldehydewith melamine is effected in the presence 01510 to 30%, based upon theweight of the product, of water;

11. A process as claimed in claim 7 wherein the amount of formaldehydeis about 2 to 5 moles per mole of melamine as contained in the fibres.

12. A process as claimedinclairn 7 wherein the heat treatment is carriedout at a-temperature of 120160 C. for a period of time necessary-to setthe resin.

13. Procession treating fibers which comprises (a) applyingrto saidfibers a 0.5 to 4% solution of a'salt-com sistingof'melamine and anoxyacid in the proportions of 0.3 to 3.0 moles of the oxy acid per moleof melamine, r

(b) exposing. the fibers to formaldehyde vapor, the amount offormaldehyde being about 2 to 5 moles per mole of melamine applied'tothe fibers, in the presence of from l0.to:30%, based upon the weight ofthe prodnet, .of water, and- (c) setting-the formed resin at a term"perature of from 120 to C.

References Cited in the file of this patent UNITED 'STATES' PATENTS2,192,074 Givens et al. Feb. 27, v1940 2,327,516 Fin k et al. Aug-24,1943 2,427,993 McLellan Sept. 23, 1947 2,479,218. Dosne Aug. 16, 19492,517,694 Merion et al. Aug. 8,1950 2,611,928 Merion et al-.- Sept. 30,1952 2,715,763 Marley Aug. 23, 1955 2,858,185 Schappel Oct. 28, 19582,894,802 Braunlich -July.14, 1959

1. PROCESS FOR PRODUCING REGENERATED CELLULOSE FILAMENTS WHICH COMPRISES(1) EXTRUDING HIGHLY XANTHATED VISCOSE, CONTAINING 3-11% BY WEIGHTCELLULOSE AND 3-13% BYY WEIGHT TOTAL ALKALI, SAID VISCOSE HAVING AXANTHATE RATIO OF AT LEAST ABOUT 50 AND A VISCOSITY OF LESS THAN ABOUT150 POISES, INTO A PRIMARY AQUEOUS ACIDIC PECIPITATION BATH TO FORM GELFILAMENTS UNDER SUBSTANTIALLY NON-STRETCHED CONDITION, SAID PRIMARY BATHCONTAINING 40-180 GMS./1. OF SULFURIC ACID, 150-400 GMS./1. OF SODIUMSULFATE AND 10-150 GMS./1. OF ZINC SULFATE AND BEING MAINTAINED AT ATEMPERATURE OF ABOUT 45 TO 80*C., SAID GEL FILAMENTS BEING CONTROLLED TOBE WITHIN 20-40 IN RESIDUAL XANTHATE RATIO, (2) PASSING THE RESULTANTFILAMENTS, UNDER SUBSTANTIALLY NON-STRETCHED CONDITION, THROUGH ASECONDARY BATH CONTAINING 5-30 GMS./1. OF SULFURIC ACID, 30-120 GMS./1.OF SODIUM SULFATE AND 0-100 GMS./1. OF ZINC SULFATE AND BEING MAINTAINEDAT A TEMPERATURE OF ABOUT 5 TO 30*C., SAID GEL FILAMENTS BEINGCONTROLLED TO BE WITHIN 20-40 IN RESIDUAL XANTHATE RATIO IMMEDIATELYPRIOR TO STRETCHING, AND 9 TAINED AT A TEMPERATURE OF ABOUT 10 50*C.,SAID (3) STRETCHING SAID FILAMENTS MORE THAN TWICE WHILE PASSING THEMTHROUGH A THIRD AND FOURTH BATH, SAID THIRD BATH BEING AT LEAST EQUAL INREGENERATING POWER TO THE SECONDARY BATH, AND CONTAINING 10-50 GMS./1.OF SULFURIC ACID, 30-120 GMS./1. OF SODUIM SULFATE AND 0-100 GMS./1. OFZINC SULFATE AND BEING MAINTHIRD BATH REDUCING THE RESIDUAL XANTHATERATIO BY AT MOST 70%, SAID FOURTH BATH CONTAINING 30-100 GMS./1. OFSULFURIC ACID AND 0-200 GMS./1. OF SODIUM SULFATE AND BEING MAINTAINEDAT A TEMPERATURE OF TO 100% AND AT SAID FOURTH BATH 10 TO 80%, AND EACHSUCCESSIVE BATH IN THE PLURALITY OF BATHS BEING AT LEAST AS STRONG INREGENERATING POWER AS ITS PRECEDING BATH. ABOVE 50*C., THE STRETCH ATSAID THIRD BATH BEING 30